[PLUG-TALK] Amber light filters (Off topic)

Keith Lofstrom keithl at gate.kl-ic.com
Sat Nov 7 15:49:59 PST 2015

I recently learned that light in the blue spectrum before
bedtime interferes with sleep.  So I am putting amber gel
filters on many of the evening light sources.   

Colored bulbs are usually just that - we have a red LED 
bulb in the bathroom, and it produces some purple and blue.

  Hint:  you can estimate color spectrum with a manufactured
  CD or DVD.  The spiral track is a decent optical grating,
  if you get the incidence angle approximately right.  LEDs
  make light in specific separated bands, not continuous
  like an incandescent filament.

Lee Filters (http://www.leefilters.com/) makes 20x24 inch
gel filter sheets in hundreds of colors for theater lights.
There are a couple of theater supply stores in the Portland
area.  I let the post office do the driving and ordered a few
colors from PNTA (http://www.pnta.com/lighting/gels/lee/ )
in Seattle.  Of the colors I purchased, the 105 color works
well with LED bulbs, and filters out all the purple and blue.  

Philips makes these silly-looking SlimStyle "bulbs", LEDs in
a circle around a disk that vaguely approximate a standard
light bulb.  Most people agree they are silly looking, which
is why Home Depot is selling them at a deep discount, three
60W-equivalent 2700K "warm" "bulbs" for $7.97 .

Because the SlimStyle bulbs are somewhat flat, I found a
cool hack - I cut a 4 inch by 8 inch slice of gel filter,
folded it in half, and taped the edges to make a 4 by 4
inch pouch.  That fits around a SlimStyle bulb nicely;
then tape the corners at the bottom to make an enclosure.

It gets warm, but not hot, and removes about 40% of the
light (all the blue and purple, part of the green, and
about 15% transmission loss from the yellow and red).
However, it is much more restful, and OK for reading.


Keith Lofstrom          keithl at keithl.com

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